Feature fill with multi-stage nucleation inhibition

ABSTRACT

Described herein are methods of filling features with tungsten, and related systems and apparatus, involving inhibition of tungsten nucleation. In some embodiments, the methods involve selective inhibition along a feature profile. Methods of selectively inhibiting tungsten nucleation can include exposing the feature to a direct or remote plasma. The methods include performing multi-stage inhibition treatments including intervals between stages. One or more of plasma source power, substrate bias power, or treatment gas flow may be reduced or turned off during an interval. The methods described herein can be used to fill vertical features, such as in tungsten vias, and horizontal features, such as vertical NAND (VNAND) wordlines. The methods may be used for both conformal fill and bottom-up/inside-out fill. Examples of applications include logic and memory contact fill, DRAM buried wordline fill, vertically integrated memory gate and wordline fill, and 3-D integration using through-silicon vias.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/163,306, filed May 18, 2015, which is incorporated by referenceherein.

BACKGROUND

Deposition of conductive materials using chemical vapor deposition (CVD)techniques is an integral part of many semiconductor fabricationprocesses. These materials may be used for horizontal interconnects,vias between adjacent metal layers, contacts between first metal layersand devices on the silicon substrate, and high aspect ratio features. Ina conventional tungsten deposition process, a substrate is heated to apredetermined process temperature in a deposition chamber, and a thinlayer of tungsten-containing materials that serves as a seed ornucleation layer is deposited. Thereafter, the remainder of thetungsten-containing material (the bulk layer) is deposited on thenucleation layer. Conventionally, the tungsten-containing materials areformed by the reduction of tungsten hexafluoride (WF₆) with hydrogen(H₂). Tungsten-containing materials are deposited over an entire exposedsurface area of the substrate including features and a field region.

Depositing tungsten-containing materials into small and, especially,high aspect ratio features may cause formation of seams and voids insidethe filled features. Large seams may lead to high resistance,contamination, loss of filled materials, and otherwise degradeperformance of integrated circuits. For example, a seam may extend closeto the field region after filling process and then open duringchemical-mechanical planarization.

SUMMARY

In one aspect, a method of inhibiting a feature on a substrate isprovided. The method may include providing a substrate including afeature having one or more feature openings and a feature interior; andperforming a multi-stage inhibition treatment comprising exposing thefeature to a plasma generated from a treatment gas in at least a firststage and a second stage with an interval between the first and secondstages, wherein one of more of a plasma source power, a substrate bias,or a treatment gas flow rate is reduced during the interval, and whereinthe inhibition treatment preferentially inhibits nucleation of a metalat the feature openings.

In some embodiments, the plasma source power, substrate bias, ortreatment gas flow rate is turned off during the interval. Themulti-stage inhibition treatment may include exposing the feature to adirect plasma while applying a bias to the substrate. In someembodiments, the plasma contains activated species of one or more ofnitrogen, hydrogen, oxygen, and carbon. The plasma may be nitrogen-basedor hydrogen-based in some embodiments. The multi-stage inhibitiontreatment in the feature may include exposing the feature to aremotely-generated plasma. A remotely-generated plasma may beradical-based with the feature having little or no ion exposure.

In some embodiments, a tungsten layer in the feature prior to themulti-stage inhibition treatment. In some embodiments, the multi-stageinhibition treatment includes treating a metal nitride surface of thefeature. In some embodiment, the method includes, after the multi-stageinhibition treatment, selectively depositing tungsten in the feature inaccordance with an inhibition profile formed by the multi-stageinhibition treatment. The method may further include repeating a cycleof the multi-stage inhibition treatments and selective deposition one ormore times to fill the feature.

The multi-stage inhibition treatment may be performed without etchingmaterial in the feature. Also, in some embodiments, feature fill may beperformed without etching material in the feature. In some embodiments,the feature is part of a 3-D structure.

At least a constriction in the feature may be preferentially inhibited.In some embodiments, a de-inhibition treatment may be performed before,after, or during the multi-stage inhibition treatment.

According to various embodiments, one of plasma source power, substratebias power, treatment gas flow, and chamber pressure during the firststage is different than during the second stage.

Another aspect relates to a method of filling a feature includingproviding a substrate including a feature having one or more featureopenings and a feature interior, performing a multi-stage inhibitiontreatment in two or more stages with an interval between the stages suchthat there is a differential inhibition profile along a feature axis;and selectively depositing tungsten in the feature in accordance withthe modified differential inhibition profile.

These and other aspects are described more fully below with reference tothe figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1G show examples of various structures that can be filledaccording to the processes described herein.

FIGS. 2A-2C are process flow diagrams illustrating certain operations inmethods of filling features with tungsten.

FIG. 2D is a graph showing growth delay time (after inhibition) as afunction of thickness of tungsten layer deposited prior to theinhibition treatment.

FIGS. 3A-3C are process flow diagrams illustrating certain operations inmethods of selective inhibition.

FIG. 3D is a graph showing inhibition modulation as function ofpre-inhibition exposure to air duration.

FIGS. 4A-4E are process flow diagrams illustrating certain operations oftreating a substrate after exposing the substrate to a nitrogen-basedplasma or other inhibition chemistry and prior to tungsten deposition.

FIG. 4F is a graph showing inhibition modulation as a function ofpost-inhibition anneal duration.

FIG. 4G is a graph comparing the effect of various de-inhibitionprocesses, with process A being a control (deposition with noinhibition).

FIG. 4H shows resistivity as a function of thickness for the tungstenfilms deposited by each of the processes of FIG. 4G.

FIGS. 5A-5C are process flow diagrams illustrating certain operations inmethods of tungsten feature fill including de-inhibition operations.

FIGS. 5D, 6, and 7 are schematic diagrams showing features at variousstages of feature fill.

FIG. 8 shows an example of source power and bias power for a multi-stageinhibition treatment.

FIG. 9 shows schematic illustrations of single- and multi-stagetreatments of 3-D structures.

FIG. 10A shows nucleation delay time as a function of inhibitiontreatment time for single-stage and multi-stage inhibition treatmentswith no bias applied to the substrate.

FIG. 10B shows nucleation delay time as a function of inhibitiontreatment time for single-stage and multi-stage inhibition treatmentswith 200 W bias power applied to the substrate.

FIG. 11A shows results of front and back side gas tuning on uniformity.

FIGS. 11B, 12A and 12B are schematic diagrams showing examples ofapparatus suitable for practicing the methods described herein.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Thepresent invention may be practiced without some or all of these specificdetails. In other instances, well known process operations have not beendescribed in detail to not unnecessarily obscure the present invention.While the invention will be described in conjunction with the specificembodiments, it will be understood that it is not intended to limit theinvention to the embodiments.

Described herein are methods of filling features with tungsten andrelated systems and apparatus. Examples of application include logic andmemory contact fill, DRAM buried wordline fill, vertically integratedmemory gate/wordline fill, and 3-D integration with through-silicon vias(TSVs). The methods described herein can be used to fill verticalfeatures, such as in tungsten vias, and horizontal features, such asvertical NAND (VNAND) wordlines. The methods may be used for conformaland bottom-up or inside-out fill.

According to various embodiments, a feature can be characterized by oneor more of narrow and/or re-entrant openings, constrictions within thefeature, and high aspect ratios. Examples of features that can be filledare depicted in FIGS. 1A-1C. FIG. 1A shows an example of across-sectional depiction of a vertical feature 101 to be filled withtungsten. The feature can include a feature hole 105 in a substrate 103.The substrate may be a silicon wafer, e.g., 200-mm wafer, 300-mm wafer,or 450-mm wafer, including wafers having one or more layers of materialsuch as dielectric, conducting, or semi-conducting material depositedthereon. In some embodiments, the feature hole 105 may have an aspectratio of at least about 2:1, at least about 4:1, at least about 6:1 orhigher. The feature hole 105 may also have a dimension near the opening,e.g., an opening diameter or line width, of between about 10 nm to 500nm, for example between about 25 nm to 300 nm. The feature hole 105 maybe referred to as an unfilled feature or simply a feature. The feature,and any feature, may be characterized in part by an axis 118 thatextends through the length of the feature, with vertically-orientedfeatures having vertical axes and horizontally-oriented features havinghorizontal axes.

FIG. 1B shows an example of a feature 101 that has a re-entrant profile.A re-entrant profile is a profile that narrows from a bottom of thefeature, a closed end of the feature, or interior of the feature to thefeature opening. According to various embodiments, the profile maynarrow gradually and/or include an overhang at the feature opening. FIG.1B shows an example of the latter, with an under-layer 113 lining thesidewall or interior surfaces of the feature hole 105. The under-layer113 can be for example, a diffusion barrier layer, an adhesion layer, anucleation layer, a combination of thereof, or any other appropriatematerial. Examples of such under-layers include titanium nitride (TiN)under-layers, titanium/titanium nitride (Ti/TiN) under-layers, andtungsten nitride (WN) under-layers. The under-layer 113 forms anoverhang 115 such that the under-layer 113 is thicker near the openingof the feature 101 than inside the feature 101.

In some embodiments, features having one or more constrictions withinthe feature may be filled. FIG. 1C shows examples of views of variousfilled features having constrictions. Each of the examples (a), (b) and(c) in FIG. 1C includes a constriction 109 at a midpoint within thefeature. The constriction 109 can be, for example, between about 15 nmto 20 nm wide. Constrictions can cause pinch off during deposition oftungsten in the feature using conventional techniques, with depositedtungsten blocking further deposition past the constriction before thatportion of the feature is filled, resulting in voids in the feature.Example (b) further includes a liner/barrier overhang 115 at the featureopening. Such an overhang could also be a potential pinch-off point.Example (c) includes a constriction 112 further away from the fieldregion than the overhang 115 in example (b). As described further below,methods described herein allow void-free fill as depicted in FIG. 1C.

Horizontal features, such as in 3-D memory structures, can also befilled. FIG. 1D shows an example of a word line 150 in a VNAND structure148 that includes a constriction 151. In some embodiments, theconstrictions can be due to the presence of pillars in a VNAND or otherstructure. FIG. 1E, for example, shows a plan view of pillars 125 in aVNAND structure, with FIG. 1F showing a simplified schematic of across-sectional depiction of the pillars 125. Arrows in FIG. 1Erepresent deposition material; as pillars 125 are disposed between anarea 127 and a gas inlet or other deposition source, adjacent pillarscan result in constrictions that present challenges in void free fill ofthe area 127.

FIG. 1G provides another example of a view horizontal feature, forexample, of a VNAND or other structure including pillar constrictions151. The example in FIG. 1G is open-ended, with material to be depositedable to enter laterally from two sides as indicated by the arrows. (Itshould be noted that example in FIG. 1G can be seen as a 2-D rendering3-D features of the structure, with the FIG. 1G being a cross-sectionaldepiction of an area to be filled and pillar constrictions shown in thefigure representing constrictions that would be seen in a plan ratherthan cross-sectional view.) In some embodiments, 3-D structures can becharacterized with the area to be filled extending along threedimensions (e.g., in the X, Y and Z-directions in the example of FIG.1F), and can present more challenges for fill than filling holes ortrenches that extend along one or two dimensions. For example,controlling fill of a 3-D structure can be challenging as depositiongasses may enter a feature from multiple dimensions.

Filling features with tungsten-containing materials may cause formationof voids and seams inside the filled features. A void is region in thefeature that is left unfilled. A void can form, for example, when thedeposited material forms a pinch point within the feature, sealing offan unfilled space within the feature preventing reactant entry anddeposition.

There are multiple potential causes for void and seam formation. One isan overhang formed near the feature opening during deposition oftungsten-containing materials or, more typically, other materials, suchas a diffusion barrier layer or a nucleation layer. An example of anoverhang is shown in FIG. 1B.

Another cause of void or seam formation that is not illustrated in FIG.1B but that nevertheless may lead to seam formation or enlarging seamsis curved sidewalls of feature holes. Features having such curvedsidewalls are also referred to as bowed features. In a bowed feature,the cross-sectional dimension of the cavity near the opening is smallerthan that inside the feature. Deposition challenges caused by thenarrowed openings of bowed features are similar to those caused byoverhangs as described above. Constrictions within a feature such asshown in FIGS. 1C, 1D and 1G also present challenges for tungsten fillwith few or no voids and seams.

Even if void free fill is achieved, tungsten in the feature may containa seam running through the axis or middle of the via, trench, line orother feature. This is because tungsten growth can begin at the sidewalland continue until the tungsten grains meet with tungsten growing fromthe opposite sidewall. This seam can allow for trapping of impuritiesincluding fluorine-containing compounds such as hydrofluoric acid (HF).During chemical mechanical planarization (CMP), coring can alsopropagate from the seam. According to various embodiments, the methodsdescribed herein can reduce or eliminate void and seam formation. Themethods described herein may also address one or more of the following:

1) Very challenging profiles: Void free fill can be achieved in mostre-entrant features using deposition-etch-deposition (dep-etch-dep)cycles as described in U.S. Pat. No. 8,435,894, incorporated byreference herein. However, depending on the dimensions and geometry,multiple dep-etch-dep cycles may be needed to achieve void-free fill.This can affect process stability and throughput. Embodiments describedherein can provide feature fill with fewer or no dep-etch-dep cycles.

2) Small features and liner/barrier impact: In cases where the featuresizes are extremely small, tuning the etch process without impacting theintegrity of a liner/barrier underlayer can be very difficult. In somecases intermittent titanium (Ti) attack can occur during a W-selectiveetch. This may be due to formation of a passivating titanium fluoride(TiF_(x)) layer during the etch.

3) Scattering at W grain boundaries: The presence of multiple W grainsinside the feature can result in electron loss due to grain boundaryscattering. As a result, actual device performance will be degradedcompared to theoretical predictions and blanket wafer results.

4) Reduced via volume for W fill: Especially in smaller and newerfeatures, a significant part of the metal contact is used up by the Wbarrier (e.g., a TiN or WN, etc. barrier). These films are typicallyhigher resistivity than W and negatively impact electricalcharacteristics like contact resistance.

FIGS. 2-4 provide overviews of various processes of tungsten featurefill that can address the above issues, with examples of tungsten fillof various features described with reference to FIGS. 5-7.

FIG. 2A is a process flow diagram illustrating certain operations in amethod of filling a feature with tungsten. The method begins at a block201 with selective inhibition of a feature. Selective inhibition, whichmay also be referred to as selective passivation, differentialinhibition, or differential passivation, involves inhibiting subsequenttungsten nucleation on a portion of the feature, while not inhibitingnucleation (or inhibiting nucleation to a lesser extent) on theremainder of the feature. For example, in some embodiments, a feature isselectively inhibited at a feature opening, while nucleation inside thefeature is not inhibited. Selective inhibition is described furtherbelow, and can involve, for example, selectively exposing a portion ofthe feature to activated species of a plasma. In certain embodiments,for example, a feature opening is selectively exposed to a plasmagenerated from molecular nitrogen gas. As discussed further below, adesired inhibition profile in a feature can be formed by appropriatelyselecting one or more of inhibition chemistry, substrate bias power,plasma power, process pressure, exposure time, and other processparameters.

Once the feature is selectively inhibited, the method can continue atblock 203 with selective deposition of tungsten according to theinhibition profile. Block 203 may involve one or more chemical vapordeposition (CVD) and/or atomic layer deposition (ALD) processes,including thermal, plasma-enhanced CVD and/or ALD processes. Thedeposition is selective in that the tungsten preferentially grows on thelesser- and non-inhibited portions of the feature. In some embodiments,block 203 involves selectively depositing tungsten in a bottom orinterior portion of the feature until a constriction is reached orpassed.

After selective deposition according to the inhibition profile isperformed, the method can continue at block 205 with filling the rest ofthe feature. In certain embodiments, block 205 involves a CVD process inwhich a tungsten-containing precursor is reduced by hydrogen to deposittungsten. While tungsten hexafluoride (WF₆) is often used, the processmay be performed with other tungsten precursors, including, but notlimited to, tungsten hexachloride (WCl₆), organo-metallic precursors,and precursors that are free of fluorine such as MDNOW(methylcyclopentadienyl-dicarbonylnitrosyl-tungsten) and EDNOW(ethylcyclopentadienyl-dicarbonylnitrosyl-tungsten). In addition, whilehydrogen can be used as the reducing agent in the CVD deposition, otherreducing agents including silane may be used in addition or instead ofhydrogen. In another embodiment, tungsten hexacarbonyl (W(CO)₆) may beused with or without a reducing agent. Unlike with ALD and pulsednucleation layer (PNL) processes described further below, in a CVDtechnique, the WF₆ and H₂ or other reactants are simultaneouslyintroduced into the reaction chamber. This produces a continuouschemical reaction of mix reactant gases that continuously forms tungstenfilm on the substrate surface. Methods of depositing tungsten filmsusing CVD are described in U.S. patent application Ser. Nos. 12/202,126,12/755,248 and 12/755,259, which are incorporated by reference herein intheir entireties for the purposes of describing tungsten depositionprocesses. According to various embodiments, the methods describedherein are not limited to a particular method of filling a feature butmay include any appropriate deposition technique.

In some embodiments, block 205 may involve continuing a CVD depositionprocess started at block 203. Such a CVD process may result indeposition on the inhibited portions of the feature, with nucleationoccurring more slowly than on the non-inhibited portions of the feature.In some embodiments, block 205 may involve deposition of a tungstennucleation layer over at least the inhibited portions of the feature.

According to various embodiments, the feature surface that isselectively inhibited can be a barrier or liner layer, such as a metalnitride layer, or it can be a layer deposited to promote nucleation oftungsten. FIG. 2B shows an example of a method in which a tungstennucleation layer is deposited in the feature prior to selectiveinhibition. The method begins at block 301 with deposition of the thinconformal layer of tungsten in the feature. The layer can facilitatesubsequent deposition of bulk tungsten-containing material thereon. Incertain embodiments, the nucleation layer is deposited using a PNLtechnique. In a PNL technique, pulses of a reducing agent, purge gases,and tungsten-containing precursor can be sequentially injected into andpurged from the reaction chamber. The process is repeated in a cyclicalfashion until the desired thickness is achieved. PNL broadly embodiesany cyclical process of sequentially adding reactants for reaction on asemiconductor substrate, including ALD techniques. PNL techniques fordepositing tungsten nucleation layers are described in U.S. Pat. Nos.6,635,965; 7,589,017; 7,141,494; 7,772,114; 8,058,170 and in U.S. patentapplication Ser. Nos. 12/755,248 and 12/755,259, which are incorporatedby reference herein in their entireties for the purposes of describingtungsten deposition processes. Block 301 is not limited to a particularmethod of tungsten nucleation layer deposition, but includes PNL, ALD,CVD, and physical vapor deposition (PVD) techniques for depositing athin conformal layer. The nucleation layer can be sufficiently thick tofully cover the feature to support high quality bulk deposition;however, because the resistivity of the nucleation layer is higher thanthat of the bulk layer, the thickness of the nucleation layer may beminimized to keep the total resistance as low as possible. Examplethicknesses of films deposited in block 301 can range from less than 10Å to 100 Å. After deposition of the thin conformal layer of tungsten inblock 301, the method can continue with blocks 201, 203, and 205 asdescribed above with reference to FIG. 2A. An example of filling afeature according to a method of FIG. 2B is described below withreference to FIG. 5D.

In some embodiments, the thickness of the layer deposited in block 301may be used to modulate the inhibition effect of the subsequentoperation. FIG. 2D shows growth delay time (after inhibition) as afunction of thickness of tungsten layer deposited prior to theinhibition treatment. The thinner the layer, the stronger the inhibitingeffect. The first data point reflects an inhibition treatment performedon a nucleation layer only. Non-conformal layers may be selectivelyinhibited, with thinner layers more strongly inhibited.

FIG. 2C shows an example of a method in which completing filling thefeature (e.g., block 205 in FIG. 2A or 3) can involve repeatingselective inhibition and deposition operations. The method can begin atblock 201, as described above with respect to FIG. 2A, in which thefeature is selectively inhibited, and continue at block 203 withselective deposition according to the inhibition profile. Blocks 201 and203 are then repeated one or more times (block 401) to complete featurefill. An example of filling a feature according to a method of FIG. 2Cis described below with reference to FIG. 6.

Still further, selective inhibition can be used in conjunction withselective deposition. Selective deposition techniques are described inU.S. Patent Publication No. 2013/0302980, referenced above.

According to various embodiments, selective inhibition can involveexposure to activated species that passivate the feature surfaces. Forexample, in certain embodiments, a tungsten (W) surface can bepassivated by exposure to a nitrogen-based or hydrogen-based plasma. Insome embodiments, inhibition can involve a chemical reaction betweenactivated species and the feature surface to form a thin layer of acompound material such as tungsten nitride (WN) or tungsten carbide(WC). In some embodiments, inhibition can involve a surface effect suchas adsorption that passivates the surface without forming a layer of acompound material. Activated species may be formed by any appropriatemethod including by plasma generation and/or exposure to ultraviolet(UV) radiation. In some embodiments, the substrate including the featureis exposed to a plasma generated from one or more gases fed into thechamber in which the substrate sits. In some embodiments, one or moregases may be fed into a remote plasma generator, with activated speciesformed in the remote plasma generator fed into a chamber in which thesubstrate sits. The plasma source can be any type of source includingradio frequency (RF) plasma source or microwave source. The plasma canbe inductively and/or capacitively-coupled. Activated species caninclude atomic species, radical species, and ionic species. In certainembodiments, exposure to a remotely-generated plasma includes exposureto radical and atomized species, with substantially no ionic speciespresent in the plasma such that the inhibition process is notion-mediated. In other embodiments, ion species may be present in aremotely-generated plasma. In certain embodiments, exposure to anin-situ plasma involves ion-mediated inhibition. For the purposes ofthis application, activated species are distinguished from recombinedspecies and from the gases initially fed into a plasma generator.

Inhibition chemistries can be tailored to the surface that will besubsequently exposed to deposition gases. For tungsten (W) surfaces, asformed for example in a method described with reference to FIG. 2B,exposure to nitrogen-based and/or hydrogen-based plasmas inhibitssubsequent tungsten deposition on the W surfaces. Other chemistries thatmay be used for inhibition of tungsten surfaces include oxygen-basedplasmas and hydrocarbon-based plasmas. For example, molecular oxygen ormethane may be introduced to a plasma generator.

As used herein, a nitrogen-based plasma is a plasma in which the mainnon-inert component is nitrogen. An inert component such as argon,xenon, or krypton may be used as a carrier gas. In some embodiments, noother non-inert components are present in the gas from which the plasmais generated except in trace amounts. Similarly, a hydrogen-based plasmais a plasma in which the main non-inert component is hydrogen. In someembodiments, inhibition chemistries may be nitrogen-containing,hydrogen-containing, oxygen-containing, and/or carbon-containing, withone or more additional reactive species present in the plasma. Forexample, U.S. patent application Ser. No. 13/016,656, incorporated byreference herein, describes passivation of a tungsten surface byexposure to nitrogen trifluoride (NF₃). Similarly, fluorocarbons such asCF₄ or C₂F₈ may be used. However, in certain embodiments, the inhibitionspecies are fluorine-free to prevent etching during selectiveinhibition.

In certain embodiments, UV radiation may be used in addition to orinstead of plasma to provide activated species. Gases may be exposed toUV light upstream of and/or inside a reaction chamber in which thesubstrate sits. Moreover, in certain embodiments, non-plasma, non-UV,thermal inhibition processes may be used. In addition to tungstensurfaces, nucleation may be inhibited on liner/barrier layers surfacessuch as TiN and/or WN surfaces. Any chemistry that passivates thesesurfaces may be used. For TiN and WN, this can include exposure tonitrogen-based or nitrogen-containing chemistries. In certainembodiments, the chemistries described above for W may also be employedfor TiN, WN, or other liner layer surfaces.

Tuning an inhibition profile can involve appropriately controlling aninhibition chemistry, substrate bias power, plasma power, processpressure, exposure time, and other process parameters. For in situplasma processes (or other processes in which ionic species arepresent), a bias can be applied to the substrate. Substrate bias can, insome embodiments, significantly affect an inhibition profile, withincreasing bias power resulting in active species deeper within thefeature. For example, 100 W DC bias on a 300 mm substrate may resultinhibition the top half of a 1500 nm deep structure, while a 700 W biasmay result in inhibition of the entire structure. The absolute biaspower appropriate a particular selective inhibition will depend on thesubstrate size, the system, plasma type, and other process parameters,as well as the desired inhibition profile, however, bias power can beused to tune top-to-bottom selectivity, with decreasing bias powerresulting in higher selectivity.

For 3-D structures in which selectivity is desired in a lateraldirection (tungsten deposition preferred in the interior of thestructure), but not in a vertical direction, bias power can be used topromote top-to-bottom deposition uniformity. Bias power may alsodecrease inhibition treatment time, by promoting faster travel of theinhibition species down the height of a 3-D structure. This can bebeneficial for throughput as well as for preventing treatment fromundesirably extending inside a word line (WL) or other lateral feature.The latter may occur for longer duration treatments.

While bias power can be used in certain embodiments as the primary oronly knob to tune an inhibition profile for ionic species, in certainsituations, other performing selective inhibition uses other parametersin addition to or instead of bias power. These include remotelygenerated non-ionic plasma processes and non-plasma processes. Also, inmany systems, a substrate bias can be easily applied to tune selectivityin a vertical but not lateral direction. Accordingly, for 3-D structuresin which lateral selectivity is desired, parameters other than bias maybe controlled, as described above. Also, in some embodiments, aninhibition treatment may be performed without a bias to preventsputtering. For example, a bias may sputter metal on the outer part of a3-D structure. The sputtering may erase the inhibition effect.

Inhibition chemistry can also be used to tune an inhibition profile,with different ratios of active inhibiting species used. For example,for inhibition of W surfaces, nitrogen may have a stronger inhibitingeffect than hydrogen; adjusting the ratio of N₂ and H₂ gas in a forminggas-based plasma can be used to tune a profile. The plasma power mayalso be used to tune an inhibition profile, with different ratios ofactive species tuned by plasma power. Process pressure can be used totune a profile, as pressure can cause more recombination (deactivatingactive species) as well as pushing active species further into afeature. Process time may also be used to tune inhibition profiles, withincreasing treatment time causing inhibition deeper into a feature.

In some embodiments, selective inhibition can be achieved by performingoperation 201 in a mass transport limited regime. In this regime, theinhibition rate inside the feature is limited by amounts of and/orrelative compositions of different inhibition material components (e.g.,an initial inhibition species, activated inhibition species, andrecombined inhibition species) that diffuse into the feature. In certainexamples, inhibition rates depend on various components' concentrationsat different locations inside the feature.

Mass transport limiting conditions may be characterized, in part, byoverall inhibition concentration variations. In certain embodiments, aconcentration is less inside the feature than near its opening resultingin a higher inhibition rate near the opening than inside. This in turnleads to selective inhibition near the feature opening. Mass transportlimiting process conditions may be achieved by supplying limited amountsof inhibition species into the processing chamber (e.g., use lowinhibition gas flow rates relative to the cavity profile anddimensions), while maintaining relative high inhibition rates near thefeature opening to consume some activated species as they diffuse intothe feature. In certain embodiment, a concentration gradient issubstantial, which may be caused relatively high inhibition kinetics andrelatively low inhibition supply. In certain embodiments, an inhibitionrate near the opening may also be mass transport limited, though thiscondition is not required to achieve selective inhibition.

In addition to the overall inhibition concentration variations insidefeatures, selective inhibition may be influenced by relativeconcentrations of different inhibition species throughout the feature.These relative concentrations in turn can depend on relative dynamics ofdissociation and recombination processes of the inhibition species. Asdescribed above, an initial inhibition material, such as molecularnitrogen, can be passed through a remote plasma generator and/orsubjected to an in-situ plasma to generate activated species (e.g.,atomic nitrogen, nitrogen ions). However, activated species mayrecombine into less active recombined species (e.g., nitrogen molecules)and/or react with W, WN, TiN, or other feature surfaces along theirdiffusion paths. As such, different parts of the feature may be exposedto different concentrations of different inhibition materials, e.g., aninitial inhibition gas, activated inhibition species, and recombinedinhibition species. This provides additional opportunities forcontrolling selective inhibition. For example, activated species aregenerally more reactive than initial inhibition gases and recombinedinhibition species. Furthermore, in some cases, the activated speciesmay be less sensitive to temperature variations than the recombinedspecies. Therefore, process conditions may be controlled in such a waythat removal is predominantly attributed to activated species. As notedabove, some species may be more reactive than others. Furthermore,specific process conditions may result in activated species beingpresent at higher concentrations near features' openings than inside thefeatures. For example, some activated species may be consumed (e.g.,reacted with feature surface materials and/or adsorbed on the surface)and/or recombined while diffusing deeper into the features, especiallyin small high aspect ratio features. Recombination of activated speciescan also occur outside of features, e.g., in the showerhead or theprocessing chamber, and can depends on chamber pressure. Therefore,chamber pressure may be specifically controlled to adjust concentrationsof activated species at various points of the chamber and features.

Flow rates of the inhibition gas can depend on a size of the chamber,reaction rates, and other parameters. A flow rate can be selected insuch a way that more inhibition material is concentrated near theopening than inside the feature. In certain embodiments, these flowrates cause mass-transport limited selective inhibition. For example, aflow rate for a 195-liter chamber per station may be between about 25sccm and 10,000 sccm or, in more specific embodiments, between about 50sccm and 1,000 sccm. In certain embodiments, the flow rate is less thanabout 2,000 sccm, less than about 1,000 sccm, or more specifically lessthan about 500 sccm. It should be noted that these values are presentedfor one individual station configured for processing a 300-mm substrate.These flow rates can be scaled up or down depending on a substrate size,a number of stations in the apparatus (e.g., quadruple for a fourstation apparatus), a processing chamber volume, and other factors.

In certain embodiments, the substrate can be heated up or cooled downbefore selective inhibition. Various devices may be used to bring thesubstrate to the predetermined temperature, such as a heating or coolingelement in a station (e.g., an electrical resistance heater installed ina pedestal or a heat transfer fluid circulated through a pedestal),infrared lamps above the substrate, igniting plasma, etc.

A predetermined temperature for the substrate can be selected to inducea chemical reaction between the feature surface and inhibition speciesand/or promote adsorption of the inhibition species, as well as tocontrol the rate of the reaction or adsorption. For example, atemperature may be selected to have high reaction rate such that moreinhibition occurs near the opening than inside the feature. Furthermore,a temperature may be also selected to control recombination of activatedspecies (e.g., recombination of atomic nitrogen into molecular nitrogen)and/or control which species (e.g., activated or recombined species)contribute predominantly to inhibition. In certain embodiments, asubstrate is maintained at less than about 300° C., or more particularlyat less than about 250° C., or less than about 150° C., or even lessthan about 100° C. In other embodiments, a substrate is heated tobetween about 300° C. and 450° C. or, in more specific embodiments, tobetween about 350° C. and 400° C. Other temperature ranges may be usedfor different types of inhibition chemistries. Exposure time can also beselected to cause selective inhibition. Example exposure times can rangefrom about 10 s to 500 s, depending on desired selectivity and featuredepth.

In some embodiments, the inhibition treatments described above aremodulated to improve selectivity and tune the inhibition profile. FIGS.3A-3C and 4A-provide examples of flow charts of selectively inhibitingtungsten deposition in a feature. FIGS. 3A-3C provide examples oftreating a substrate prior to exposing the substrate to annitrogen-based plasma or other inhibition chemistry. First, in FIG. 3A,the process begins by exposing a substrate including a feature to acontrolled vacuum break (350). As used herein, a vacuum break refers toa period wherein the substrate is not under vacuum. In block 350, thesubstrate may be exposed to atmospheric pressure, for example, in astorage cassette (e.g., a front opening unified pod or FOUP) or in aloadlock. In some embodiments, the substrate may be exposed toatmospheric temperature and/or gasses (i.e., air). Alternatively,temperature and gas composition may be controlled. The duration of block350 may be controlled to effectively modulate the subsequent inhibitiontreatment. Next, the substrate is exposed to an inhibition treatment asdiscussed above (352). In a particular example, the substrate is exposedto a nitrogen-based plasma. The process shown in FIG. 3A may beperformed as part of block 201 in a process as shown in FIGS. 2A-2C. Insome embodiments, block 350 is performed after deposition of a thin filmin the feature, for example as shown in block 301 of FIG. 2B. In oneexample, a thin tungsten film may be deposited in a feature in a firstvacuum chamber, followed by a controlled vacuum break in a FOUP orloadlock, followed by exposure to a nitrogen-based plasma in a secondvacuum chamber.

The process of FIG. 3B is similar to that of FIG. 3A, with a substrateincluding a feature exposed to an oxidizing chemistry (354). In someembodiments, block 354 may be performed outside a reaction chamber, forexample in a FOUP or loadlock. Alternatively, block 354 may involveexposing a substrate to an oxidizing gas, such as O₂, O₃, CO₂, H₂O, etc.in a process chamber. Block 354 may be performed under vacuum or atatmospheric pressure. According to various embodiments, block 354 may ormay not involve the use of plasma- or UV-activated species. For example,block 354 may involve exposing the substrate to O₂ under non-plasmaconditions such that the O₂ is not activated. Block 354 is followed byexposing the substrate to an inhibition treatment (352). In a particularexample, the substrate is exposed to a nitrogen-based plasma. Blocks 354and 352 may be performed in the same chamber or different chambers. Theprocess shown in FIG. 3B may be performed as part of block 201 in aprocess as shown in FIGS. 2A-2C. In some embodiments, block 354 isperformed after deposition of a thin film in the feature, for example asshown in block 301 of FIG. 2B.

In some embodiments, block 350 in FIG. 3A or block 354 in FIG. 3B ininvolves formation of an oxide film in the feature. For example, inimplementations in which there is a thin conformal tungsten filmdeposited in the feature (e.g., as in block 301 of FIG. 2B), tungstenoxide (WO_(x)) may be formed in the feature. In some embodiments, WO_(x)formation in a feature is non-conformal.

FIG. 3D shows growth delay of a tungsten deposition performed after thefollowing sequence: a) deposition of tungsten layer, b) exposure to air(vacuum break) and c) exposure to a nitrogen-based plasma inhibitingtreatment. As shown in FIG. 3D, an air break modulates the inhibitioneffect of the nitrogen-based plasma by lessening the effect.

The process of FIG. 3C involves exposing a substrate including a featureto a reactive chemistry (356). Examples of reactive chemistries includereducing chemistries (e.g., B₂H₆, SiH₄) and tungsten-containingchemistries (e.g., WF₆, WCl₆). Block 354 is followed by exposing thesubstrate to an inhibition treatment (352). In a particular example, thesubstrate is exposed to a nitrogen-based plasma. Blocks 356 and 352 maybe performed in the same chamber or different chambers. The processshown in FIG. 3C may be performed as part of block 201 in a process asshown in FIGS. 2A-2C. In some embodiments, block 356 is performed afterdeposition of a thin film in the feature, for example as shown in block301 of FIG. 2B. Block 356 may be referred to as a soak, and is generallya non-plasma operation.

Table 1, below, compares inhibition performed after a diborane soak withinhibition performed after no soak. For both processes, a 100 Å tungstennucleation layer was deposited, followed by the soak/no soak operation,followed by exposure to a nitrogen plasma. The deposition operationfollowing the inhibition treatment was 300 seconds (including delay).

TABLE 1 Inhibition with and without pre-inhibition treatment diboranesoak Pre-inhibition 300 second W 300 second W B₂H₆ soaking deposition:thickness deposition: delay (seconds) (Å) (seconds) 0 897 221 15100 >300 sThe results in Table 1 indicate that the B₂H₆ rich surface modulates theinhibition effect by increasing it.

FIGS. 4A-4E provide examples of treating a substrate after exposing thesubstrate to a nitrogen-based plasma or other inhibition chemistry andprior to tungsten deposition. The treatment modulates the inhibition.First, in FIG. 4A, the process includes exposing a substrate including afeature to an inhibition treatment as discussed above (450). In aparticular example, the substrate is exposed to a nitrogen-based plasma.Next, the substrate is annealed (452). Block 452 may involve raising thetemperature, e.g., by at least 50° C., 100° C. or 200° C. The annealingmay be performed in an inert ambient, or in an oxidizing environment,for example. Blocks 450 and 452 may be performed in the same chamber ordifferent chambers. The process shown in FIG. 4A may be performed aspart of block 201 in a process as shown in FIGS. 2A-2C. Block 452 may beperformed in a chamber where a subsequent tungsten deposition is to beperformed. In some embodiments, block 450 may be performed as part ofblock 352 in FIGS. 3A-3C, i.e., after a modulation pretreatment.

The process of FIG. 4B involves exposing a substrate including a featureto a reactive chemistry (454) after exposing it to an inhibitiontreatment (450) as described above. Examples of reactive chemistriesinclude reducing chemistries (e.g., B₂H₆, SiH₄) and tungsten-containingchemistries (e.g., WF₆, WCl₆). Blocks 450 and 454 may be performed inthe same chamber or different chambers. The process shown in FIG. 4B maybe performed as part of block 201 in a process as shown in FIGS. 2A-2C.In some embodiments, the reactive chemistry in block 454 is one or morecompounds used in a subsequent tungsten deposition operation. In someembodiments, block 450 may be performed as part of block 352 in FIGS.3A-3C, i.e., after a modulation pretreatment. Block 454 may be referredto as a soak, and is generally a non-plasma operation.

The process of FIG. 4C involves exposing a substrate including a featureto an oxidizing chemistry (456) after exposing it to an inhibitiontreatment (450) as described above. Examples of oxidizing chemistriesinclude O₂, O₃, CO₂, and H₂O. Block 456 may be performed at the same ordifferent temperature than block 450. According to various embodiments,block 456 may or may not involve the use of plasma- or UV-activatedspecies. For example, block 456 may involve exposing the substrate to O₂under non-plasma conditions such that the O₂ is not activated. Blocks450 and 456 may be performed in the same chamber or different chambers.The process shown in FIG. 4C may be performed as part of block 201 in aprocess as shown in FIGS. 2A-2C. In some embodiments, block 450 may beperformed as part of block 352 in FIGS. 3A-3C, i.e., after a modulationpretreatment.

The process of FIG. 4D involves exposing a substrate including a featureto a sputtering gas (458) after exposing it to an inhibition treatment(450) as described above. Examples of sputtering gases include Ar andH₂. Blocks 450 and 458 may be performed in the same chamber or differentchambers. The process shown in FIG. 4D may be performed as part of block201 in a process as shown in FIGS. 2A-2C. In some embodiments, block 450may be performed as part of block 352 in FIGS. 3A-3C, i.e., after amodulation pretreatment.

The process of FIG. 4E involves exposing a substrate to one or moretungsten precursor/reducing agent cycles without depositing tungsten(460) after exposing it to an inhibition treatment (450). A tungstenprecursor reducing agent cycle involves alternating pulses of a tungstenprecursor and a reducing agent. The sequence may be similar to a PNL orALD mechanism of depositing a tungsten nucleation layer. However, incontrast to a nucleation layer deposition, substantially no tungsten (notungsten to less than an atomic layer of tungsten) is deposited duringblock 460. Pulse times, tungsten precursor concentrations, and/or dosageamounts during the one or more tungsten precursor pulses may be adjustedto ensure that substantially no tungsten deposits. For example, one ormore of these parameters may be lower than during a tungsten nucleationlayer cycle. In another example, reducing agent pulse time may begreater than tungsten precursor pulse time, e.g., 1.5 to 5 timesgreater.

As described in U.S. Pat. No. 8,058,170, incorporated by referenceherein, exposing a deposited tungsten nucleation layer to alternatingcycles of a reducing agent/tungsten precursor without depositingtungsten acts as a low resistivity treatment, lowering the resistivityof the tungsten nucleation layer. As discussed further below withrespect to FIGS. 4G and 4H, block 460 may lower resistivity and improvestress of the deposited tungsten film in addition to modulating theinhibition effect.

FIG. 4F shows growth delay of a tungsten deposition performed after thefollowing sequence: a) deposition of a tungsten layer, b) exposure to anitrogen-based plasma inhibiting treatment, and c) exposure to a thermalanneal. As shown in FIG. 4F, annealing modulates the inhibition effectof the nitrogen plasma by lessening the effect.

Table 2, below, compares inhibition prior to a diborane soak withinhibition performed prior to no soak. For both processes, a tungstenlayer was deposited, followed by exposure to a nitrogen plasma, followedby a soak/no soak operation.

TABLE 2 Inhibition with and without post-inhibition treatment diboranesoak Post-inhibition W W B₂H₆ soaking deposition thickness growth delay(seconds) (Å) (seconds) 0 564 1044 3 3187 170The results in Table 2 indicate that the post-inhibition B₂H₆ soakingmodulates the inhibition effect by decreasing it. This may be becausethe soaking with a reactive gas increases the nucleation sites.

In another example of a process that modulates an inhibition effect, asubstrate including a feature may exposed to an H-containing plasmaafter exposing it to an inhibition treatment as described above.Examples of H-containing plasmas include remote and in situ plasmasgenerated from hydrogen (H₂) gas. Exposure to an H₂ plasma reduces theinhibition effect.

Various post-inhibition treatments above may be used to decrease theinhibition effect and can be referred to as “de-inhibition” treatments.FIGS. 5A-5C are examples of flow charts that show operations in usingsuch treatments to fill a feature with tungsten.

First, FIG. 5A is a process flow diagram showing an example of a methodof filling a feature in accordance with certain embodiments. The processbegins at block 501 by treating a substrate to inhibit tungstendeposition on the substrate. Examples of inhibition treatments are givenabove, and include exposure to nitrogen-based plasmas. Block 501 mayinvolve non-conformal inhibition of one or more features on thesubstrate. Tungsten deposition is then performed at block 503 on theinhibited substrate surfaces. In some embodiments, block 503 involves aselective deposition according to a non-conformal inhibition profile.The substrate is treated to reduce the inhibiting effect. (Block 505).As noted above, such a treatment may be referred to as a de-inhibitiontreatment. Examples of such treatments including annealing and reducingagent soaks are described above. Tungsten is then deposited onde-inhibited substrate surfaces. (Block 507).

In some embodiments, one or more features on the substrate may becompletely filled with tungsten after block 503. The de-inhibitiontreatment in block 505 may be performed on, for example, tungsten infield regions of the substrate or in features that are not completelyfilled by block 505. For example, block 503 may fill smaller features,leaving larger features partially unfilled. By performing ade-inhibition treatment, the tungsten deposition rate may besignificantly increased. This can be advantageous for surfaces in whichselective deposition is not desired.

In FIG. 5B, tungsten is deposited in a feature (449). Block 449 involvespartially filling the feature with tungsten. In some embodiments, block449 involves depositing a thin conformal film as described above withrespect to block 301 of FIG. 2B. The substrate is then exposed to aninhibition treatment (450) as described above. After exposing thesubstrate to an inhibition treatment, the substrate is exposed to ade-inhibition treatment that reduces the inhibition effect. Examples ofde-inhibition treatments are given above and include an H-containingplasma, a reducing agent thermal soak, and a thermal anneal. Selectivedeposition of tungsten in then performed in accordance with theinhibition profile (203) as described above.

In FIG. 5C, blocks 449 and 450 are performed as described above withrespect to FIG. 5B. After block 450, a selective deposition is performedin accordance with the inhibition profile obtained in block 450 (203).The selective deposition is followed by exposing the substrate to ade-inhibition treatment (458) as described above. Another selectivedeposition of tungsten is performed in accordance with the inhibitionprofile obtained in block 458 (203). In some embodiments, block 458 mayremove the inhibition effect, such the deposition in block 203 is notpreferential or selective to a particular region of the feature.

The process shown in FIG. 5B can be used to reduce the inhibition effectacross all features to be filled on a substrate. The process shown inFIG. 5C allows complete fill of some features, e.g., narrow or highaspect ratio or otherwise challenging features before reducing theinhibition effect on partially filled features.

FIG. 4G is a graph comparing various de-inhibition processes, withprocess A being a control (deposition—no inhibition). Conditions for thefirst deposition (Dep1), second deposition (Dep2) and inhibitiontreatment (for processes B-E) were the same, with only potentialde-inhibition treatments varied. The process conditions are given inTable 3, below.

TABLE 3 Inhibition and De-inhibition Processes Process Dep1 InhibitionDe-Inhibition Dep2 A 2 × (B/W) none none 2 × (B/W) in in H2 at H2 at300° C. + 300° C. 395° C. CVD B 2 × (B/W) N2 plasma, no Diborane soak, 2× (B/W) in in H2 at bias, 3 seconds, 60 s (12 × H2 at 300° C. + 300° C.2 mT, 2000 W 5 s B2H6), 395° C. CVD LFRF 395° C. C 2 × (B/W) N2 plasma,no Silane soak, 2 × (B/W) in in H2 at bias, 3 seconds, 60 s (12 × H2 at300° C. + 300° C. 2 mT, 2000 W 5 s SiH4), 395° C. CVD LFRF 395° C. D 2 ×(B/W) N2 plasma, no 2 × (2 s 2 × (B/W) in in H2 at bias, 3 seconds,B2H6/W + H2 at 300° C. + 300° C. 2 mT, 2000 W 1 s WF6)) 395° C. CVD LFRFE 2 × (B/W) N2 plasma, no 6 × (2 s 2 × (B/W) in in H2 at bias, 3seconds, B2H6/W + H2 at 300° C. + 300° C. 2 mT, 2000 W 1 s WF6)) 395° C.CVD LFRF

Referring to FIG. 4G, it can be seen that the de-inhibition for a silanesoak (process C) is smaller than the remaining processes, if present atall. Compared to control process A, processes B (60 s diborane soak) andE (6 diborane/tungsten precursor pulse cycles) have the same depositionthicknesses, indicating that these processes erase the inhibition effectcompletely. Process D (2 diborane/tungsten precursor pulse cycles)results in significant de-inhibition.

FIG. 4H shows resistivity as a function of thickness for the tungstenfilms deposited by each of the processes shown above in Table 3.Notably, process D, which resulted in significant de-inhibition andtungsten deposition, results in low resistivity. Table 4 below showsstress (GPa) for 150 Angstrom and 600 Angstrom films deposited byprocesses A, B, and E.

TABLE 4 Stress of Films Deposited by Various Processes Process Stress150 Angstrom film Stress 600 Angstrom film A 2.48 2.24 B 3.47 2.17 E2.48 2.06As shown in Table 4, process E results in the film having the loweststress.

As described above, aspects of the disclosure can be used for VNANDwordline (WL) fill. While the below discussion provides a framework forvarious methods, the methods are not so limited and can be implementedin other applications as well, including logic and memory contact fill,DRAM buried wordline fill, vertically integrated memory gate/wordlinefill, and 3D integration (TSV).

FIG. 1F, described above, provides an example of a VNAND wordline (WL)structure to be filled. As discussed above, feature fill of thesestructures can present several challenges including constrictionspresented by pillar placement. In addition, a high feature density cancause a loading effect such that reactants are used up prior to completefill.

Various methods are described below for void-free fill through theentire wordline. In certain embodiments, low resistivity tungsten isdeposited. FIG. 5D shows a sequence in which non-conformal selectiveinhibition is used to fill in the interior of the feature before pinchoff. In FIG. 5D, a structure 500 is provided with a liner layer surface502. The liner layer surface 502 may be for example, TiN or WN. Next, aW nucleation layer 504 is conformally deposited on the liner layer 502.A PNL process as described above can be used. Note that in someembodiments, this operation of depositing a conformal nucleation layermay be omitted. Next, the structure is exposed to an inhibitionchemistry to selectively inhibit portions 506 of the structure 500. Inthis example, the portions 506 through the pillar constrictions 151 areselectively inhibited. Inhibition can involve for example, exposure to adirect (in-situ) plasma generated from a gas such as N₂, H₂, forminggas, NH₃, O₂, CH₄, etc. Other methods of exposing the feature toinhibition species are described above. Next, a CVD process is performedto selectively deposit tungsten in accordance with the inhibitionprofile: bulk tungsten 510 is preferentially deposited on thenon-inhibited portions of the nucleation layer 504, such thathard-to-fill regions behind constrictions are filled. The remainder ofthe feature is then filled with bulk tungsten 510. As described abovewith reference to FIG. 2A, the same CVD process used to selectivelydeposit tungsten may be used to remainder of the feature, or a differentCVD process using a different chemistry or process conditions and/orperformed after a nucleation layer is deposited may be used.

In some embodiments, methods described herein may be used for tungstenvia fill. FIG. 6 shows an example of a feature hole 105 including aunder-layer 113, which can be, for example, a metal nitride or otherbarrier layer. A tungsten layer 653 is conformally deposited in thefeature hole 105, for example, by a PNL and/or CVD method. (Note thatwhile the tungsten layer 653 is conformally deposited in the featurehole 105 in the example of FIG. 6, in some other embodiments, tungstennucleation on the under-layer 113 can be selectively inhibited prior toselective deposition of the tungsten layer 653.) Further deposition onthe tungsten layer 653 is then selectively inhibited, forming inhibitedportion 655 of the tungsten layer 653 near the feature opening. Tungstenis then selectively deposited by a PNL and/or CVD method in accordancewith the inhibition profile such that tungsten is preferentiallydeposited near the bottom and mid-section of the feature. Depositioncontinues, in some embodiments with one or more selective inhibitioncycles, until the feature is filled. As described above, in someembodiments, the inhibition effect at the feature top can be overcome bya long enough deposition time, while in some embodiments, an additionalnucleation layer deposition or other treatment may be performed tolessen or remove the passivation at the feature opening once depositionthere is desired. Note that in some embodiments, feature fill may stillinclude formation of a seam, such as seam 657 depicted in FIG. 6. Inother embodiments, the feature fill may be void-free and seam-free. Evenif a seam is present, it may be smaller than obtained with aconventionally filled feature, reducing the problem of coring duringCMP. The sequence depicted in the example of FIG. 6 ends post-CMP with arelatively small void present.

In some embodiments, the processes described herein may be usedadvantageously even for features that do not have constrictions orpossible pinch-off points. For example, the processes may be used forbottom-up, rather than conformal, fill of a feature. FIG. 7 depicts asequence in which a feature 700 is filled by a method according tocertain embodiments. A thin conformal layer of tungsten 753 is depositedinitially, followed by selective inhibition to form inhibited portions755, layer 753 at the bottom of the feature not treated. CVD depositionresults in a bulk film 757 deposited on at the bottom of the feature.This is then followed by repeated cycles of selective CVD deposition andselective inhibition until the feature is filled with bulk tungsten 757.Because nucleation on the sidewalls of the feature is inhibited exceptnear the bottom of the feature, fill is bottom-up. In some embodiments,different parameters may be used in successive inhibitions to tune theinhibition profile appropriately as the bottom of the feature growscloser to the feature opening. For example, a bias power and/ortreatment time may be decreased is successive inhibition treatments.

According to various embodiments, the inhibition treatments describedherein may be single stage or multi-stage treatments. A multi-stagetreatment may use several short stages rather than one longer stage. Astage may be defined by one or more of source power, bias power,treatment gas flow rate or chamber pressure, with intervals betweenstages. Each stage may have the same or different source power, biaspower, treatment gas flow rate, chamber pressure, and stage duration.Further, the duration of successive intervals may be the same ordifferent. FIG. 8 shows an example of source power and bias power for amulti-stage inhibition treatment. In the example of FIG. 8, stages 801,803, and 805 are separated by purges. The plasma source power andsubstrate bias power are on during each stage and off during theintervals between stages. As discussed further below, turning off theplasma and/or bias during an inhibition treatment as shown in FIG. 8 canreduce sputtering and de-inhibition.

FIG. 8 shows one example of a multi-stage treatment. Stages 801, 803 and805 are separated by intervals in which no treatment occurs. During aninterval, one or more of source power, bias power, and treatment gasflow may be stopped. In the example of FIG. 8, source power and biaspower are pulsed on and off, on during treatment and off during aninterval. Source power, bias power, treatment time, pressure, and gasflow may be the same for each stage or be varied. An interval mayinclude a purge in some embodiments. In addition to or instead of on/offpulses of a power or gas flow, a power or a gas flow may be reducedduring an interval and increased during a stage. In some embodiments, notreatment occurs during an interval.

A multi-stage treatment may reduce sputtering and de-inhibition ascompared to a single stage treatment. In some embodiments, a stage istimed such that plasma species are able to selectively inhibit portionsof a structure (as described above) with the stage ending prior totreatment species developing enough energy to sputter. For 3-Dstructures, each stage may be timed such that species go verticallyrather than laterally. Multi-stage treatments may be used withtreatments that use remote, radical-based plasmas as well as in-situion-containing plasmas. In some embodiments, radical and other speciesmay be purged out during an interval. A de-inhibition treatment asdescribed above may be performed before, during, or after a multi-stageinhibition treatment. In some embodiments, a multi-stage inhibitiontreatment is performed with no de-inhibition treatments performed duringthe multi-stage inhibition treatment, and with a second or successivestage performed directly after a preceding stage or a precedinginterval. During an interval, process conditions may remain the same asduring a stage except with one or more of a source power and a gas flowrate turned off or reduced.

Each stage of a multi-stage treatment may be engineered with differentsource power, bias power, time, flow, and pressure to tune an inhibitionprofile. In an example, bias power may be:

Stage 1: 0 Watts (W) 5 seconds (5 s)

Stage 2: 100 W 5 s

Stage 3: 100 W 5 s

In some embodiments, a multi-stage treatment may include multiple stagesperformed sequentially with no interval between them. One or more of theparameters listed above may be modulated from one stage to the next. Insome embodiments, a stage may include heating or cooling with differentgases to control an inhibition profile.

FIG. 9 shows schematic illustrations of treatments of 3-D structures at901, 902 and 903. At 901, a 3-D structure is shown undergoing a singlestage treatment with no bias. The treatment species flow paths(represented by arrows) extend laterally into the features (see 910),which can reduce fill inside the features. At 902, a 3-D structure isshown undergoing a single stage treatment with bias. Sputtering andde-inhibition may occur at 912. At 903, a 3-D structure is shownundergoing a multi-stage treatment as depicted in FIG. 8. The treatmentis largely in the vertical direction without sputtering.

In single or multi-stage treatments, a pulsed plasma may be used. One orboth of the source plasma power and bias power may be pulsed. If bothare pulsed, they may or may not have the same frequency and duty cycle.In the same or other embodiments, a treatment gas may be pulsed. In amulti-stage treatment that uses a pulsed plasma (i.e., the plasma ineach stage is pulsed), in each stage, the pressure, flow, source andbias powers, time, frequency, and duties may be the same or vary fromstage to stage. Further, pulsed plasma may be implemented in inhibitionmodulation treatments as described above.

According to various embodiments, an etch may be performed in connectionwith an inhibition treatment and selective deposition. For example, aprocess sequence may include deposition(dep1)-etch-inhibition-deposition (dep2). After the first tungstendeposition, the tungsten in the feature may be etched to form aprofile/thickness that facilitates inhibition. For example, as describedabove, thinner tungsten films result in more inhibition. Accordingly, adep1-etch-inhibition-dep2 sequence may be used to support further fillimprovement and overall film thickness management. Selected locations inthe feature (for example, a field region or sidewall in a 3D structure)may be etched preferentially to increase inhibition at those regions. Inthe same or other embodiments, an etch may be performed after depositionto improve uniformity, wafer bow, and film thickness management. In anexample, a process sequence may include dep1-inhibition-dep2-etch ordep1-etch-inhibition-dep2-etch. An etch may be performed in aninhibition chamber or in another chamber. Examples of etch processesthat may be performed are described in U.S. Pat. Nos. 8,119,527;8,835,317; and 9,034,768; which are incorporated by reference herein.

In some embodiments, the inhibition treatments described herein may beused to improve feature fill using low stress films. Typical low stressfilms suffer from fill degradation. The inhibition treatments describedherein may be used to improve fill in such cases. A small void may beacceptable in such cases as long as stress and other defect-causingcharacteristics are adequately managed.

In some embodiments, a high temperature anneal may be performed aftertungsten deposition to allow fluorine to diffuse out. For example, in aWL structure, a high temperature anneal may be performed before themouth of the WL is pinched off. Inhibition may be performed after theanneal in some embodiments.

According to various embodiments, a deposition subsequent to aninhibition (“dep2”) may be tuned to improve uniformity. In someembodiments, a non-reactive (e.g., Ar) back side flow may be addedduring such a deposition. Without being bound by any particular theory,it is believed that a back side gas can improve uniformity by reducingdeposition at the edge of a substrate. In some embodiments, tungstenprecursor flow and pressure modulation on a substrate center and edge ina dep2 step helps improve inhibition stack film uniformity. Tungstengrowth delay time is sensitive to tungsten precursor flow and pressure.In some embodiments, uniformity may be improved by cleaning an edge ringor forgoing a precoat of tungsten on the edge ring. It is believed thatHF or other product of tungsten deposition may result in de-inhibitionat the wafer edge. Forgoing a pre-coat or cleaning an edge ring may beavoid tungsten CVD on the edge ring and reduce this effect.

EXPERIMENTAL

3D VNAND features similar to the schematic depiction in FIG. 1F wereexposed to plasmas generated from N₂H₂ gas after deposition of aninitial tungsten seed layer. The substrate was biased with a DC bias,with bias power varied from 100 W to 700 W and exposure time variedbetween 20 s and 200 s. Longer time resulted in deeper and widerinhibition, with higher bias power resulting in deeper inhibition.

Table E1 shows effect of treatment time. All inhibition treatments usedexposure to a direct LFRF 2000 W N₂H₂ plasma with a DC bias of 100 W onthe substrate.

TABLE E1 Effect of treatment time on inhibition profile InitialInhibition Tungsten Treatment Subsequent Selective Layer Time DepositionDeposition A Nucleation + None 400 s CVD at Non-selective 30 s CVD at300° C. deposition 300° C. B same as A 60 s same as A Non-selectivedeposition C same as A 90 s same as A Yes - deposition only from bottomof feature to slightly less than vertical midpoint. Lateral deposition(wider) at bottom of feature. D same as A 140 s  same as A No depositionWhile varying treatment time resulted in vertical and lateral tuning ofinhibition profile as described in Table 1 (split C), varying bias powercorrelated higher to vertical tuning of inhibition profile, with lateralvariation a secondary effect.

As described above, the inhibition effect may be overcome by certain CVDconditions, including longer CVD time and/or higher temperatures, moreaggressive chemistry, etc. Table E2 below, shows the effect of CVD timeon selective deposition.

TABLE E2 Effect of CVD time on selective deposition Subsequent InitialCVD Depo- Tungsten Inhibition sition Time Selective Layer Treatment(300° C.) Deposition E Nucleation + H₂N₂ 2000 W 0 no deposition 30 s CVDat RF direct plasma, 300° C. 90 s, 100 W DC bias F same as E same as E200 s Yes - small amount of deposition extending about ⅙ height offeature from bottom G same as E same as E 400 s Yes - deposition onlyfrom bottom of feature to slightly less than vertical midpoint. Lateraldeposition wider at bottom of feature. H same as E same as E 700 s Yes -deposition through full height of feature, with lateral deposition widerat bottom of feature

Single-stage and multi-stage inhibition treatments were performed for nobias inhibition and 200 W bias inhibition processes. The followingprocess conditions were used:

Deposition 1: 100 Angstroms at 100° C.

Treatment: 20 sccm N₂, 100 sccm Ar, 500 W LF RF in situ plasma

Deposition 2: 300 seconds at 350° C.

FIG. 10A shows the results of the no-bias inhibition comparison. Totalinhibition treatment times were 6 seconds and 14 seconds. For themulti-stage comparison, the 6 second treatment was performed in three 2second treatments, and the 14 second treatment was performed in seven 2second treatments. The multi-stage treatment results in more delay(greater inhibition) than the single stage. This may be because asputtering de-inhibition effect is reduced. FIG. 10B shows the resultsof the biased comparison. Total inhibition treatment times were 6seconds, 10 seconds and 14 seconds, with the multi-stage treatmentsperformed in 2 second stages. Compared to the no-bias results, themulti-stage biased inhibition treatment shows a greater effect oversingle stage.

FIG. 11A shows results of front and back side gas tuning on uniformity.

Process A: front side 19000 sccm H2/back side: 13000 sccm H2, no Ar,26.8% NU

Process B: front side: 25000 sccm H2/back side: 4000 sccm H2, 2000 sccmAr, 2.4% NU

Apparatus

Any suitable chamber may be used to implement this novel method.Examples of deposition apparatuses include various systems, e.g., ALTUSand ALTUS Max, available from Novellus Systems, Inc. of San Jose,Calif., or any of a variety of other commercially available processingsystems.

FIG. 11B illustrates a schematic representation of an apparatus 1100 forprocessing a partially fabricated semiconductor substrate in accordancewith certain embodiments. The apparatus 1100 includes a chamber 1118with a pedestal 1120, a shower head 1114, and an in-situ plasmagenerator 1116. The apparatus 1100 also includes a system controller1122 to receive input and/or supply control signals to various devices.

In certain embodiments, a inhibition gas and, if present, inert gases,such as argon, helium and others, can be supplied to the remote plasmagenerator 1106 from a source 1102, which may be a storage tank. Anysuitable remote plasma generator may be used for activating the etchantbefore introducing it into the chamber 1118. For example, a RemotePlasma Cleaning (RPC) units, such as ASTRON® i Type AX7670, ASTRON® eType AX7680, ASTRON® ex Type AX7685, ASTRON® hf-s Type AX7645, allavailable from MKS Instruments of Andover, Mass., may be used. An RPCunit is typically a self-contained device generating weakly ionizedplasma using the supplied etchant. Embedded into the RPC unit a highpower RF generator provides energy to the electrons in the plasma. Thisenergy is then transferred to the neutral inhibition gas moleculesleading to temperature in the order of 2000K causing thermaldissociation of these molecules. An RPC unit may dissociate more than60% of incoming molecules because of its high RF energy and specialchannel geometry causing the gas to adsorb most of this energy.

In certain embodiments, an inhibition gas is flown from the remoteplasma generator 1106 through a connecting line 1108 into the chamber1118, where the mixture is distributed through the shower head 1114. Inother embodiments, an inhibition gas is flown into the chamber 1118directly completely bypassing the remote plasma generator 1106 (e.g.,the apparatus 1100 does not include such generator). Alternatively, theremote plasma generator 1106 may be turned off while flowing theinhibition gas into the chamber 1118, for example, because activation ofthe inhibition gas is not needed or will be supplied by an in situplasma generator. Inert gases 1112 may be mixed in some embodiments in amixing bowl 1110.

The shower head 1114 or the pedestal 1120 typically may have an internalplasma generator 1116 attached to it. In one example, the generator 1116may be High Frequency (HF) generator capable of providing between about0 W and 10,000 W at frequencies between about 1 MHz and 100 MHz. Inanother example, the generator 1116 is a Low Frequency (LF) generatorcapable of providing between about 0 W and 10,000 W at frequencies aslow as about 100 KHz. In a more specific embodiment, a HF generator maydeliver between about 0 W to 5,000 W at about 13.56 MHz. The RFgenerator 816 may generate in-situ plasma to active inhibition species.In certain embodiments, the RF generator 1116 can be used with theremote plasma generator 1106 or not used. In certain embodiments, noplasma generator is used during deposition.

The chamber 1118 may include a sensor 1124 for sensing various processparameters, such as degree of deposition, concentrations, pressure,temperature, and others. The sensor 1124 may provide information onchamber conditions during the process to the system controller 1122.Examples of the sensor 1124 include mass flow controllers, pressuresensors, thermocouples, and others. The sensor 1124 may also include aninfra-red detector or optical detector to monitor presence of gases inthe chamber and control measures.

Deposition and selective inhibition operations can generate variousvolatile species that are evacuated from the chamber 1118. Moreover,processing is performed at certain predetermined pressure levels thechamber 1118. Both of these functions are achieved using a vacuum outlet1126, which may be a vacuum pump.

In certain embodiments, a system controller 1122 is employed to controlprocess parameters. The system controller 1122 typically includes one ormore memory devices and one or more processors. The processor mayinclude a CPU or computer, analog and/or digital input/outputconnections, stepper motor controller boards, etc. Typically there willbe a user interface associated with system controller 1122. The userinterface may include a display screen, graphical software displays ofthe apparatus and/or process conditions, and user input devices such aspointing devices, keyboards, touch screens, microphones, etc.

In certain embodiments, the system controller 1122 controls thesubstrate temperature, inhibition gas flow rate, power output of theremote plasma generator 1106 and/or in situ plasma generator 1116,pressure inside the chamber 1118 and other process parameters. Thesystem controller 1122 executes system control software including setsof instructions for controlling the timing, mixture of gases, chamberpressure, chamber temperature, and other parameters of a particularprocess. Other computer programs stored on memory devices associatedwith the controller may be employed in some embodiments.

The computer program code for controlling the processes in a processsequence can be written in any conventional computer readableprogramming language: for example, assembly language, C, C++, Pascal,Fortran or others. Compiled object code or script is executed by theprocessor to perform the tasks identified in the program. The systemsoftware may be designed or configured in many different ways. Forexample, various chamber component subroutines or control objects may bewritten to control operation of the chamber components necessary tocarry out the described processes. Examples of programs or sections ofprograms for this purpose include process gas control code, pressurecontrol code, and plasma control code.

The controller parameters relate to process conditions such as, forexample, timing of each operation, pressure inside the chamber,substrate temperature, inhibition gas flow rates, etc. These parametersare provided to the user in the form of a recipe, and may be enteredutilizing the user interface. Signals for monitoring the process may beprovided by analog and/or digital input connections of the systemcontroller 1122. The signals for controlling the process are output onthe analog and digital output connections of the apparatus 1100. Furtherdescription of a system controller such as system controller 1122 isprovided below.

Multi-Station Apparatus

FIG. 12A shows an example of a multi-station apparatus 1200. Theapparatus 1200 includes a process chamber 1201 and one or more cassettes1203 (e.g., Front Opening Unified Pods) for holding substrates to beprocessed and substrates that have completed processing. The chamber1201 may have a number of stations, for example, two stations, threestations, four stations, five stations, six stations, seven stations,eight stations, ten stations, or any other number of stations. Thenumber of stations in usually determined by a complexity of theprocessing operations and a number of these operations that can beperformed in a shared environment. FIG. 12A illustrates the processchamber 1201 that includes six stations, labeled 1211 through 1216. Allstations in the multi-station apparatus 1200 with a single processchamber 1201 are exposed to the same pressure environment. However, eachstation may have a designated reactant distribution system and localplasma and heating conditions achieved by a dedicated plasma generatorand pedestal, such as the ones illustrated in FIG. 11B.

A substrate to be processed is loaded from one of the cassettes 1203through a load-lock 1205 into the station 1211. An external robot 1207may be used to transfer the substrate from the cassette 1203 and intothe load-lock 1205. In the depicted embodiment, there are two separateload locks 1205. These are typically equipped with substratetransferring devices to move substrates from the load-lock 1205 (oncethe pressure is equilibrated to a level corresponding to the internalenvironment of the process chamber 1201) into the station 1211 and fromthe station 1216 back into the load-lock 1205 for removal from theprocess chamber 1201. A mechanism 1209 is used to transfer substratesamong the processing stations 1211-1216 and support some of thesubstrates during the process as described below.

In certain embodiments, one or more stations may be reserved for heatingthe substrate. Such stations may have a heating lamp (not shown)positioned above the substrate and/or a heating pedestal supporting thesubstrate similar to one illustrated in FIG. 11B. For example, a station1211 may receive a substrate from a load-lock and be used to pre-heatthe substrate before being further processed. Other stations may be usedfor filling high aspect ratio features including deposition andselective inhibition operations.

After the substrate is heated or otherwise processed at the station1211, the substrate is moved successively to the processing stations1212, 1213, 1214, 1215, and 1216, which may or may not be arrangedsequentially. The multi-station apparatus 1200 can be configured suchthat all stations are exposed to the same pressure environment. In sodoing, the substrates are transferred from the station 1211 to otherstations in the chamber 1201 without a need for transfer ports, such asload-locks.

In certain embodiments, one or more stations may be used to fillfeatures with tungsten-containing materials. For example, stations 1212may be used for an initial deposition operation, station 1213 may beused for a corresponding selective inhibition operation. In theembodiments where a deposition-inhibition cycle is repeated, stations1214 may be used for another deposition operations and station 915 maybe used for another inhibition operation. Station 1216 may be used forthe final filling operation. It should be understood that anyconfigurations of station designations to specific processes (heating,filling, and removal) may be used. In some implementations, any of thestations can be dedicated to one or more of PNL (or ALD) deposition,selective inhibition, and CVD deposition.

As an alternative to the multi-station apparatus described above, themethod may be implemented in a single substrate chamber or amulti-station chamber processing a substrate(s) in a single processingstation in batch mode (i.e., non-sequential). In this aspect of theinvention, the substrate is loaded into the chamber and positioned onthe pedestal of the single processing station (whether it is anapparatus having only one processing station or an apparatus havingmulti-stations running in batch mode). The substrate may be then heatedand the deposition operation may be conducted. The process conditions inthe chamber may be then adjusted and the selective inhibition of thedeposited layer is then performed. The process may continue with one ormore deposition-inhibition cycles (if performed) and with the finalfilling operation all performed on the same station. Alternatively, asingle station apparatus may be first used to perform only one of theoperation in the new method (e.g., depositing, selective inhibition,final filling) on multiple substrates after which the substrates may bereturned back to the same station or moved to a different station (e.g.,of a different apparatus) to perform one or more of the remainingoperations.

Multi-Chamber Apparatus

FIG. 12B is a schematic illustration of a multi-chamber apparatus 1220that may be used in accordance with certain embodiments. As shown, theapparatus 1220 has three separate chambers 1221, 1223, and 1225. Each ofthese chambers is illustrated with two pedestals. It should beunderstood that an apparatus may have any number of chambers (e.g., one,two, three, four, five, six, etc.) and each chamber may have any numberof chambers (e.g., one, two, three, four, five, six, etc.). Each chamber1221-1225 has its own pressure environment, which is not shared betweenchambers. Each chamber may have one or more corresponding transfer ports(e.g., load-locks). The apparatus may also have a shared substratehandling robot 1227 for transferring substrates between the transferports and one or more cassettes 1229.

As noted above, separate chambers may be used for depositing tungstencontaining materials and selective inhibition of these depositedmaterials in later operations. Separating these two operations intodifferent chambers can help to substantially improve processing speedsby maintaining the same environmental conditions in each chamber. Achamber does not need to change its environment from conditions used fordeposition to conditions used for selective inhibition and back, whichmay involve different chemistries, different temperatures, pressures,and other process parameters. In certain embodiments, it is faster totransfer partially manufactured semiconductor substrates between two ormore different chambers than changing environmental conditions of thesechambers. Still further, one or more chambers may be used to etch.

In some implementations, a controller is part of a system, which may bepart of the above-described examples. Such systems can comprisesemiconductor processing equipment, including a processing tool ortools, chamber or chambers, a platform or platforms for processing,and/or specific processing components (a wafer pedestal, a gas flowsystem, etc.). These systems may be integrated with electronics forcontrolling their operation before, during, and after processing of asemiconductor wafer or substrate. The electronics may be referred to asthe “controller,” which may control various components or subparts ofthe system or systems. The controller, depending on the processingrequirements and/or the type of system, may be programmed to control anyof the processes disclosed herein, including power, intensity, andexposure times. In an integrated tool, the controller may also controlprocesses such as processing gases, temperature settings (e.g., heatingand/or cooling), pressure settings, vacuum settings, power settings,radio frequency (RF) generator settings, RF matching circuit settings,frequency settings, flow rate settings, fluid delivery settings,positional and operation settings, wafer transfers into and out of atool and other transfer tools and/or load locks connected to orinterfaced with a specific system.

Broadly speaking, the controller may be defined as electronics havingvarious integrated circuits, logic, memory, and/or software that receiveinstructions, issue instructions, control operation, enable cleaningoperations, enable endpoint measurements, and the like. The integratedcircuits may include chips in the form of firmware that store programinstructions, digital signal processors (DSPs), chips defined asapplication specific integrated circuits (ASICs), and/or one or moremicroprocessors, or microcontrollers that execute program instructions(e.g., software). The system software may be designed or configured inmany different ways. For example, various chamber component subroutinesor control objects may be written to control operation of the chambercomponents necessary to carry out the inventive processes. Examples ofprograms or sections of programs for this purpose include substratepositioning code, treatment compound control code, pressure controlcode, heater control code, and RF control code. In one embodiment, thecontroller includes instructions for performing processes of thedisclosed embodiments according to methods described above. The computerprogram code for controlling the processes can be written in anyconventional computer readable programming language: for example,assembly language, C, C++, Pascal, Fortran, or others. Compiled objectcode or script is executed by the processor to perform the tasksidentified in the program.

Program instructions may be instructions communicated to the controllerin the form of various individual settings (or program files), definingoperational parameters for carrying out a particular process on or for asemiconductor wafer or to a system. The operational parameters may, insome embodiments, be part of a recipe defined by process engineers toaccomplish one or more processing steps during the fabrication of one ormore layers, materials, metals, oxides, silicon, silicon dioxide,surfaces, circuits, and/or dies of a wafer.

The controller, in some implementations, may be a part of or coupled toa computer that is integrated with, coupled to the system, otherwisenetworked to the system, or a combination thereof. For example, thecontroller may be in the “cloud” or all or a part of a fab host computersystem, which can allow for remote access of the wafer processing. Thecomputer may enable remote access to the system to monitor currentprogress of fabrication operations, examine a history of pastfabrication operations, examine trends or performance metrics from aplurality of fabrication operations, to change parameters of currentprocessing, to set processing steps to follow a current processing, orto start a new process. In some examples, a remote computer (e.g. aserver) can provide process recipes to a system over a network, whichmay include a local network or the Internet. The remote computer mayinclude a user interface that enables entry or programming of parametersand/or settings, which are then communicated to the system from theremote computer. In some examples, the controller receives instructionsin the form of data, which specify parameters for each of the processingsteps to be performed during one or more operations. It should beunderstood that the parameters may be specific to the type of process tobe performed and the type of tool that the controller is configured tointerface with or control. Thus as described above, the controller maybe distributed, such as by comprising one or more discrete controllersthat are networked together and working towards a common purpose, suchas the processes and controls described herein. An example of adistributed controller for such purposes would be one or more integratedcircuits on a chamber in communication with one or more integratedcircuits located remotely (such as at the platform level or as part of aremote computer) that combine to control a process on the chamber.

Without limitation, example systems may include a plasma etch chamber ormodule, a deposition chamber or module, a spin-rinse chamber or module,a metal plating chamber or module, a clean chamber or module, a beveledge etch chamber or module, a physical vapor deposition (PVD) chamberor module, a chemical vapor deposition (CVD) chamber or module, anatomic layer deposition (ALD) chamber or module, an atomic layer etch(ALE) chamber or module, an ion implantation chamber or module, a trackchamber or module, and any other semiconductor processing systems thatmay be associated or used in the fabrication and/or manufacturing ofsemiconductor wafers.

As noted above, depending on the process step or steps to be performedby the tool, the controller might communicate with one or more of othertool circuits or modules, other tool components, cluster tools, othertool interfaces, adjacent tools, neighboring tools, tools locatedthroughout a factory, a main computer, another controller, or tools usedin material transport that bring containers of wafers to and from toollocations and/or load ports in a semiconductor manufacturing factory.There may be a user interface associated with controller. The userinterface may include a display screen, graphical software displays ofthe apparatus and/or process conditions, and user input devices such aspointing devices, keyboards, touch screens, microphones, etc.

Patterning Method/Apparatus:

The apparatus/process described hereinabove may be used in conjunctionwith lithographic patterning tools or processes, for example, for thefabrication or manufacture of semiconductor devices, displays, LEDs,photovoltaic panels and the like. Typically, though not necessarily,such tools/processes will be used or conducted together in a commonfabrication facility. Lithographic patterning of a film typicallycomprises some or all of the following steps, each step enabled with anumber of possible tools: (1) application of photoresist on a workpiece,i.e., substrate, using a spin-on or spray-on tool; (2) curing ofphotoresist using a hot plate or furnace or UV curing tool; (3) exposingthe photoresist to visible or UV or x-ray light with a tool such as awafer stepper; (4) developing the resist so as to selectively removeresist and thereby pattern it using a tool such as a wet bench; (5)transferring the resist pattern into an underlying film or workpiece byusing a dry or plasma-assisted etching tool; and (6) removing the resistusing a tool such as an RF or microwave plasma resist stripper.

The invention claimed is:
 1. A method comprising: providing a substrateincluding a feature having one or more feature openings and a featureinterior; and performing a multi-stage inhibition treatment comprisingexposing the feature to a plasma generated from a treatment gas inmultiple stages and multiple intervals, with successive stages separatedby one of the multiple intervals, wherein one or more of a plasma sourcepower, a substrate bias power, or a treatment gas flow rate is reducedat the start of each interval and increased at the end of the interval,and wherein the inhibition treatment preferentially inhibits nucleationof a metal at the feature openings.
 2. The method of claim 1, whereinthe multi-stage inhibition treatment comprises exposing the feature to adirect plasma while applying a bias to the substrate.
 3. The method ofclaim 1, wherein the plasma contains one or more of nitrogen, hydrogen,oxygen, and carbon activated species.
 4. The method of claim 1, whereinthe plasma is nitrogen-based or hydrogen-based.
 5. The method of claim1, wherein the multi-stage inhibition treatment in the feature comprisesexposing the feature to a remotely-generated plasma.
 6. The method ofclaim 1, further comprising depositing a tungsten layer in the featureprior to the multi-stage inhibition treatment.
 7. The method of claim 1,further comprising, after the multi-stage inhibition treatment,selectively depositing tungsten in the feature in accordance with aninhibition profile formed by the multi-stage inhibition treatment. 8.The method of claim 7, further comprising repeating a cycle of themulti-stage inhibition treatment and selective deposition one or moretimes to fill the feature.
 9. The method of claim 1, wherein themulti-stage inhibition treatment comprises treating a metal nitridesurface of the feature.
 10. The method of claim 1, wherein themulti-stage inhibition treatment is performed without etching materialin the feature.
 11. The method of claim 1, wherein the feature fill isperformed without etching material in the feature.
 12. The method ofclaim 1, wherein the feature is part of a 3-D structure.
 13. The methodof claim 1, wherein at least a constriction in the feature ispreferentially inhibited.
 14. The method of claim 1, wherein one ofplasma source power, substrate bias power, treatment gas flow, andchamber pressure during a first stage of the multi-stage inhibitiontreatment is different than during a second stage of the multi-stageinhibition treatment.
 15. The method of claim 1, wherein plasma sourcepower is reduced at the start of each interval and increased at the endof the interval.
 16. The method of claim 1, wherein substrate bias poweris reduced at the start of each interval and increased at the end of theinterval.
 17. The method of claim 1, wherein treatment gas flow rate isreduced at the start of each interval and increased at the end of theinterval.
 18. The method of claim 1, wherein one of plasma source power,substrate bias power, and treatment gas flow during a first stage of themulti-stage inhibition treatment is greater than during a second stageof the multi-stage inhibition treatment, wherein the second stage isperformed after a first stage.
 19. The method of claim 1, wherein moreof the plasma source power, the substrate bias power, or the treatmentgas flow rate is turned off during each interval and on during eachstage.